1. Field of the Invention
The present invention relates to a wrist type blood pressure meter cuff comprising a fluid bag filled with fluid such as air for oppressing a selected artery of the wrist, and a fixing member for fixing the fluid bag to the wrist.
2. Description of the Prior Art
The wrist on which a wrist type blood pressure meter is worn includes two arteries, the radial artery and ulnar artery, and it is general to oppress both of them when measuring the blood pressures in the wrist type blood pressure meter. However, the radial artery and ulnar artery at the wrist are somewhat deeply seated between the two bones of radius and ulna and parallel tendons. In certain users, by the conventional cuff, the oppressing pressure of the fluid bag does not reach sufficiently to the arteries, and the arteries are not oppressed sufficiently, and accurate blood pressure measurements may not be obtained. As compared with the brachial artery which was traditionally measured because there is no tendon around one bone and it is relatively easy to oppress, the carpal arteries are deeply seated as mentioned above and are not easily reached by the oppressing pressure of the fluid bag.
Besides, a large oppressing pressure is needed for oppressing two arteries, and the user suffers a large oppressing pressure during measurement and it is not comfortable for the user.
To solve these problems, it has been proposed to oppress only one selected artery out of the two arteries running in the wrist and measure blood pressures (for example, see patent document 1). The cuff used in this method of blood pressure measurement has a shape suited to oppress its fluid bag only to one of the two arteries in the wrist, this fluid bag is fitted to the inside of a band as a fixing member.
The patent document 1 is JP-A 61-11019.
To oppress only one selected artery and measure blood pressures, it is required to detect pulse waves of the selected artery only. That is, pulse waves of other non-selected artery must be prevented from mixing into the desired pulse waves to be detected.
When the cuff is composed as described above, as shown in FIG. 9A, before a fluid bag 41 is inflated with air, pressure is applied to neither a selected artery 62 nor a non-selected artery 64. When air is charged in the fluid bag 41 and as the fluid bag 41 is inflated, the oppressing pressure of the fluid bag 41 is applied to the selected artery 62 (FIG. 9B). As the fluid bag 41 is further expanded, the gap between the fixing member 30 and outer periphery of the wrist 65 is eliminated, and the fixing member 30 applies a force to tighten the entire wrist 65 (FIG. 9C). As a result, the non-selected artery 64 is also oppressed by the fixing member 30, and pulsations of the non-selected artery are mixed with the pulsations of the selected artery 62 necessary for measurement, and measurement of blood pressures is disturbed.